1. Field of the Invention
This invention relates generally electronic equipment, such as computers, and, more particularly, to apparatus used during insertion and extraction of circuit boards from electronic systems.
2. Background Information
Electronic systems such as computers are typically constructed in a modular fashion from circuit boards, each circuit board generally performing a specific function. Each circuit board requires multiple electrical connections, which are generally provided by two part multi-contact electrical connectors. One part of the connector is mounted to the circuit board, while a mating part of the connector may be attached to another component of the system such as a rack, a chassis, a cable, or another circuit board (e.g., backplane circuit board). Successful mating of connector parts is needed for reliable electrical connections in the system.
A number of mechanisms are known for injecting a circuit board into a chassis or extracting a circuit board from a chassis. Such mechanisms may include lever arms pivotally coupled to the circuit board and arranged to engage projections formed on the chassis. Guide formations may be provided on the chassis to receive the circuit board and to guide the circuit board into position such that electrical connector parts mate with one another. The lever arms may be arranged on the circuit board such that when the lever arms are actuated, the circuit board is provided with a biasing force that serves to move the circuit board toward the rear of the chassis, thereby mating the parts of the electrical connector.
For circuit boards with connectors having a relatively large number of pins, large insertion forces may be required to mate the connector parts. For example, a large board may contain several multi-contact connectors, each connector containing several hundred individual contacts. Each contact requires the application of an insertion force to seat the contact. Thus, the total insertion force required to seat a large board may be 65 pounds or more. Moreover, individual contacts are easily damaged if the mating connector parts are not properly aligned when they come into contact with each other. This problem is especially acute where large forces are required to mate the connector parts.
Typically, a system may include multiple circuit boards that are installed in a parallel spaced relationship to one another. In some cases, the parallel circuit boards may be commonly coupled to another circuit board (e.g., a backplane). The commonly coupled circuit board may provide electrical connections between motherboards.
It is sometimes advantageous to specify an order of installation of circuit boards into a system and an order of removal of circuit boards from the system. For example, it may be desirable to install a motherboard on a backplane before installing a daughterboard on the motherboard, or to remove a daughterboard from a motherboard before removing the motherboard from a backplane. In addition, it may be desirable to ensure that one circuit board (e.g., a motherboard) is fully installed before another circuit board (e.g., a daughterboard) is installed. For example, if a motherboard is not fully installed when a daughterboard is coupled to the motherboard, both the motherboard and the daughterboard may end up in an improper position relative to other components of the system (e.g., other circuit boards, chassis walls, etc.) In some case, improper positioning of a circuit board may cause misalignment or interference of the circuit board relative to other components, which may damage the circuit board or other components. User documentation such as service manuals may provide detailed instructions to promote proper installation and removal of circuit boards, and in the proper sequence. In addition, circuit board assemblies may themselves have labels displaying instructions for proper installation and removal the circuit boards. In practice, however, personnel may fail to review or correctly implement such instructions.